The present invention relates to a process for the production of polyisobutenes from a gas feed stream comprising monomers of mixed butenes as well as saturated C.sub.4 hydrocarbons and optionally some lower and higher hydrocarbons.
A widely used known process for polymerizing low molecular weight olefins consists in passing the olefins through a catalyst suspended in a liquid slurry. The resulting polymer contains significant amounts of catalyst and must, therefore, be subsequently treated by costly and time-consuming techniques to remove the catalytic material which it contains.
To obviate this drawback, it has been suggested to carry out the polymerization of olefinic feeds in the presence of a solid catalyst by using the fluidized bed technique as described in U.S. Pat. No. 2,446,619. However, this process has not proven itself effective to form materials beyond dimers.
U.S. Pat. No. 3,017,400 teaches the polymerization of olefins by passing the feed through a catalyst material, such as aluminum chloride and ferric chloride. However, these catalysts are not very active and they have a relatively short life. In a similar fashion, U.S. Pat. No. 3,558,737 discloses that catalysts useful for hydrocarbon conversions, for example, isomerization, alkylation, polymerization, can be prepared by activating alumina, either alone or in admixture with a chlorinated organic compound or with an organic compound in the presence of chlorine. These catalysts are suitable in a plurality of hydrocarbon processes, but when employed for polymerizing olefins, they yield only lower molecular weight polymers. Moreover, when used for polymerizing feeds comprising mixed butenes, these catalysts give polymers containing large amounts of poly-n-butenes and small amounts of polyisobutenes. These catalysts are also only active for relatively short periods of life.
There is, therefore, a need for a process which can be undertaken for long periods of time and which allows the selective polymerization of isobutene from a gas feed stream containing monomers of mixed butenes. It is also highly desirable to obtain liquid polyisobutenes having a molecular weight of at least 280. The latter are valuable products for many uses, for example, as additives in lubricating oils, insulating oils and the like due to their increased viscosity when compared with the corresponding poly-n-butenes having the same molecular weight.